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71.
Prof. Dr. Tomoaki Tanase Dr. Kanako Nakamae Yume Okawa Mami Hamada Dr. Arimasa Matsumoto Prof. Dr. Takayuki Nakajima Prof. Dr. Takuya Nakashima Prof. Dr. Tsuyoshi Kawai 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(8):e202104060
A P-stereogenic linear tetraphosphine tetraoxide, (R,R)- or (S,S)-dpmppm(=O)4, was synthesized to prepare C2 dinuclear M(hfa)3 complexes (M=Eu, Tb, Y) as the first example of lanthanide(III) complexes with P-chiral multidentate phosphine oxides. The mononuclear M(hfa)3 complexes (M=Eu, Y) with a P-chiral diphosphine dioxide, tpdpb(=O)2, were also prepared, and comparison of their photophysical properties for the EuIII complexes revealed that significant chiral induction from the P-chiral centers arises on the achiral M(hfa)3 units through intramolecular π-π stacking constraint in the dinuclear system. 相似文献
72.
In single‐molecule force spectroscopy (SMFS), many studies have focused on the elasticity and conformation of polymer chains, but little attention has been devoted to the dynamic properties of single polymer chains. In this study, we measured the energy dissipation and elastic properties of single polystyrene (PS) chains in toluene, methanol, and N,N‐dimethylformamide using a homemade piezo‐control and data acquisition system externally coupled to a commercial atomic force microscope (AFM), which provided more accurate information regarding the dynamic properties of the PS chains. We quantitatively measured the chain length‐dependent changes in the stiffness and viscosity of a single chain using a phenomenological model consistent with the theory of viscoelasticity for polymer chains in dilute solution. The effective viscosity of a polymer chain can be determined using the Kirkwood model, which is independent of the intrinsic viscosity of the solvent and dependent on the interaction between the polymer and solvent. The results indicated that the viscosity of a single PS chain is dominated by the interaction between the polymer and solvent. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019 , 57, 1736–1743 相似文献
73.
Masahito Segi Hiroaki Yamamoto Takeyoshi Hori Tadashi Nakajima 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1):599-602
Selenoaldehydes and selenoketones, generated by thermal retro-Diels-Alder reaction of their cycloadducts with cyclopentadiene, reacted with oxygen-functionalized conjugated dienes such as 1-acetoxy-1,3-butadiene, Danishefsky's diene, and 1,4-diacetoxy-1,3-butadiene to give the corresponding cycloadducts in good yields regioselectively. 相似文献
74.
Dr. Masashi Nakamura Yo Nakajima Prof. Dr. Nagahiro Hoshi Dr. Hiroo Tajiri Dr. Osami Sakata 《Chemphyschem》2013,14(11):2426-2431
The oxidation processes of a Pt(111) electrode in alkaline electrolytes depend on non‐specifically adsorbed ions according to in situ X‐ray diffraction and infrared spectroscopic measurements. In an aqueous solution of LiOH, an OHad adlayer is formed in the first oxidation step of the Pt(111) electrode as a result of the strong interaction between Li+ and OHad, whereas Pt oxidation proceeds without OHad formation in CsOH solution. Structural analysis by X‐ray diffraction indicates that Li+ is strongly protective against surface roughening caused by subsurface oxidation. Although Cs+ is situated near the Pt surface, the weak protective effect of Cs+ results in irreversible surface roughening due to subsurface oxidation. 相似文献
75.
Shunsuke Kotani Masaya Ito Hirono Nozaki Masaharu Sugiura Masamichi Ogasawara Makoto Nakajima 《Tetrahedron letters》2013
An application of a hypervalent silicon complex, generated from a chiral phosphine oxide catalyst and silicon tetrachloride, to the enantioselective organocatalytic Morita–Baylis–Hillman reaction is described. A chloride anion liberated from the hypervalent silicon complex smoothly generated a γ-chloro silyl enol ether that subsequently reacted with an aldehyde to afford the Baylis–Hillman adducts in good yields and with good enantioselectivities. 相似文献
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78.
Facile Insertion of Carbon Dioxide into Cu2(μ‐H) Dinuclear Units Supported by Tetraphosphine Ligands
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Kanako Nakamae Dr. Bunsho Kure Prof. Takayuki Nakajima Prof. Yasuyuki Ura Prof. Tomoaki Tanase 《化学:亚洲杂志》2014,9(11):3106-3110
Reactions of meso‐bis[(diphenylphosphinomethyl)phenylphosphino]methane (dpmppm) with CuI species in the presence of NaBH4 afforded di‐ and tetranuclear copper hydride complexes, [Cu2(μ‐H)(μ‐dpmppm)2]X ( 1 ) and [Cu4(μ‐H)2(μ4‐H)(μ‐dpmppm)2]X ( 2 ) (X=BF4, PF6). Complex 1 undergoes facile insertion of CO2 (1 atm) at room temperature, leading to a formate‐bridged dicopper complex [Cu2(μ‐HCOO)(dpmppm)2]X ( 3 ). The experimental and DFT theoretical studies clearly demonstrate that CO2 insertion into the Cu2(μ‐H) unit occurred with the flexible dicopper platform. Complex 2 also undergoes CO2 insertion to give a formate‐bridged complex, [Cu4(μ‐HCOO)3(dpmppm)2]X, during which the square Cu4 framework opened up to a linear tetranuclear chain. 相似文献
79.
Takumi Nakajima Ken Takano Hiromu Maeda Dr. Yohei Ogiwara Prof. Dr. Norio Sakai 《化学:亚洲杂志》2021,16(24):4103-4107
The results of this study show that disilathiane is an effective mediator in the synthesis of alkyl aryl sulfides with disulfides and alkyl carboxylates. Mechanistic studies suggest that disilathiane promotes cleavage of the sulfur–sulfur bond of disulfides to generate thiosilane as a key intermediate. Diselenides were also applicable to this transformation to produce the corresponding selenides. 相似文献
80.
Tsuji S Yoshinari Y Kawai E Nakajima K Park HS Shindo D 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2007,188(2):380-386
A new method of surface microscopy is proposed, which combines three-dimensional electron spin resonance imaging by magnetic resonance force microscopy (MRFM) and topographic imaging of the sample surface by scanning force microscopy (SFM). In order to demonstrate its potential for the identification of microscale objects, the individual and combined images are used to provide the locations, shapes and spin density distributions of target phantom objects. We report spatial resolution in MRFM of 2.8 x 2.8 x 2.0 microm(3). This could be improved to the theoretical limit of 0.08 x 0.08 x 0.04 microm(3) through reduction of the thermal noise by cooling to cryogenic temperatures approximately 0.5K. We believe that this type of microscopy will become a very useful tool for the investigation of anomalies induced in surfaces by materials buried below the surface. 相似文献